Redmine with plugins
http://www.redmine.org/
http://www.redmine.org/wiki/redmine/Plugins
We use it commercially in our firm:
http://rknowsys.com/projmgmt/
We liked it so much that we have donated cash and also are in the process of
writing a couple of plugins - for backup and a couple of other features.
Thanks,
kc
K. C. Ramakrishna
www.rknowsys.com